Layers of the Ocean Oceans cover two thirds of our Earth. There are five oceans which all flow into each North other. Sea Oceans should not Irish be confused with seas. Sea Seas are smaller than oceans and are usually located where the land and English ocean meet. Look at this map of the Channel United Kingdom as an example: What Are the Layers of the Ocean? Oceans are made of five layers which all Atlantic Ocean have different temperatures, amount of light and creatures living within them. Page 1 of 10 visit twinkl.com Layers of the Ocean Sunlight Zone – up to 200m below the surface of the ocean There is plenty of sunlight and heat in this zone although they both get less the deeper you go. Due to the light and warmth, this is the layer with the most life, including: • seaweed which plant feeders eat; • fast swimming hunters, such as dolphins (mammals which breathe air) and salmon; • coral reefs. Humans enjoy this layer for activities such as swimming, fishing and sea transport. Twilight Zone – up to 1000m below the surface of the ocean This layer has only faint sun rays reaching it due to its depth. It is home to some of the strangest sea animals, which often have large eyes to help them see, including: • the sea cucumber; • the swordfish; • the wolf eel; • the octopus. No plants grow within this layer so creatures either feed by filtering the water or by hunting other creatures at speed. Humans can dive to this layer but must wear protective suits due to the extreme pressure and the lack of warmth. Midnight Zone – up to 4000m below the surface of the ocean The Midnight Zone makes up 90% of the ocean. It gets its name from the fact that sunlight cannot reach this layer but some light can be seen from the creatures that produce their own light, such as: • the anglerfish; • the viperfish; • the jellyfish. There are large numbers of creatures living within this layer and many of them are red or black due to the low light levels. Some creatures, such as the sperm whale, dive to these depths to hunt for food. Page 2 of 10 visit twinkl.com Layers of the Ocean Abyss – up to 6000m below the surface of the ocean This layer contains three quarters of the ocean bed, which is covered with thick mud made from the remains of dead animals. The sunlight cannot reach this layer at all, so it is pitch-black and near freezing. Very few creatures live here but those that do are mainly transparent, blind invertebrates, such as: • sea stars; • amphipods (shrimps); • squid. The Trench – up to 11,000m below the surface of the ocean The Trench is also known as the ocean floor. It is a series of narrow, underwater valleys which can only be explored using specialist scientific equipment. This is due to the high pressure and the near freezing temperatures. There is no natural light in this zone but different creatures can be found, such as sea stars. Did you know…? The deepest part of the ocean ever to be explored by man is in the Mariana Trench. It is almost 11,000m deep! The ocean is an incredible part of our world and sea scientists hope that it will be explored more as technology advances. Page 3 of 10 visit twinkl.com Layers of the Ocean Questions 1. How deep is the Twilight Zone? Tick one. up to 200m below the surface of the ocean up to 1000m below the surface of the ocean up to 4000m below the surface of the ocean up to 6000m below the surface of the ocean 2. Which creatures are found in the Abyss? Tick three. sea stars amphipods jellyfish squid 3. How much of the ocean bed is contained within the Abyss? 4. How do creatures feed in the Twilight Zone? 5. Find and copy an adjective which tells you that the Abyss is dark. 6. Summarise what you have learned about the Trenches, in 30 words or less. 7. In your own words, explain why the Sunlight Zone was given that name. 8. Which layer of the ocean would you most like to visit? Give two reasons to explain your choice. Page 10 of 10 visit twinkl.com Layers of the Ocean Answers Answers 1. How deep is the Twilight Zone? Tick one. up to 200m below the surface of the ocean up to 1000m below the surface of the ocean up to 4000m below the surface of the ocean up to 6000m below the surface of the ocean 2. Which creatures are found in the Abyss? Tick three. sea stars amphipods jellyfish squid 3. How much of the ocean bed is contained within the Abyss? Three quarters of the ocean bed is contained within the Abyss. 4. How do creatures feed in the Twilight Zone? Filtering the water; hunting other creatures at speed. 5. Find and copy an adjective which tells you that the Abyss is dark. Pitch-black 6. Summarise what you have learned about the Trenches, in 30 words or less. Pupils’ own responses, such as: Also called the ocean floor, the Trench is up to 11,000m below the surface. High pressure and extreme cold mean it can only be explored with scientific equipment. Some creatures are found here even though there is no natural light. 7. In your own words, explain why the Sunlight Zone was given that name. Pupils’ own responses, such as: The Sunlight Zone has that name because it is closest to the surface so is the layer that gets the most sunlight. 8. Which layer of the ocean would you most like to visit? Give two reasons to explain your choice. Pupils’ own responses, such as: I would like to visit the Midnight Zone because I’d like to see that creatures that produce their own light and I’d also love to see a huge sperm whale diving for food. Page 1 of 9 visit twinkl.com Layers of the Ocean Oceans cover two thirds of our Earth, making up 362 million km² of the Earth’s surface. There are five oceans (the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Antarctic or Southern Ocean and the Arctic Ocean) but they are not separated; North they all flow into each other. The Pacific Ocean is Sea Irish the largest and deepest of all the oceans. It is so Sea deep in places that the world’s tallest mountain, Everest, would sink without a trace! English Channel Oceans should not be confused with seas. Seas are smaller than oceans and are usually located where Atlantic the land and ocean meet as seen on this map of the Ocean United Kingdom: What Are the Layers of the Ocean? Oceans are made of five distinct layers which all have their own characteristics, including temperature, light and the creatures living within them. Page 4 of 10 visit twinkl.com Layers of the Ocean Epipelagic Zone (Sunlight Zone) This layer is from the surface to around 200m below the surface of the ocean so sunlight is able to reach it. There is plenty of light and heat in this zone although they both decrease the deeper you go. Due to the light and warmth, this is the layer with the most life, including: • seaweed which plant feeders eat; • fast swimming hunters, such as dolphins (mammals which breathe air) and salmon; • coral reefs. Humans enjoy this layer for activities such as swimming, fishing and sea transport. Mesopelagic Zone (Twilight Zone) This layer reaches to 1000m below the surface of the ocean so only faint sun rays reach it. It is home to some of the strangest sea animals, which often have large eyes to help them see, including the sea cucumber, swordfish, wolf eel and octopus. No plants grow within this layer so creatures either feed by filtering the water or hunting other creatures at speed. Humans can dive to this layer but have to wear protective suits due to the extreme pressure and lack of warmth. Bathypelagic Zone (Midnight Zone) The Midnight Zone, which makes up 90% of the ocean, is up to 4000m below the surface of the ocean. It gets its name from the fact that sunlight cannot reach this layer. Some plants and creatures such as, the anglerfish, the viperfish and the jellyfish produce their own light (bioluminescent). This light is used to hunt their prey. Although the pressure in this layer is high, there are large numbers of creatures living within it. Many of the animals are red or black due to the low light levels. Some creatures, such as the sperm whale, dive to these depths to hunt for food. Page 5 of 10 visit twinkl.com Layers of the Ocean Abyssopelagic Zone (Abyss) This layer is up to 6000m below the surface of the ocean and contains 75% of the ocean bed, which is covered with thick mud made from the remains of dead animals. The sunlight cannot reach this layer at all so it is pitch-black and near freezing. Very few creatures live here but those that do are mainly transparent, blind invertebrates, such as sea stars, amphipods (shrimps) and squid. Hadalpelagic Zone (The Trenches) The Trench is up to 11,000m below the surface of the ocean and is also known as the ocean floor. It is actually a series of underwater canyons (or narrow valleys) which can only be explored using specialist scientific equipment. This is due to the high pressure and near freezing temperatures.